Four hot DOGs eaten up with the EVN

TL;DR

This study used the European VLBI Network to observe four hot dust-obscured galaxies, confirming active nuclei and revealing both compact and extended radio emissions, providing insights into their AGN activity and galaxy evolution.

Contribution

First VLBI observations of hot DOGs at 1.7 GHz, detecting compact radio features and revealing the coexistence of AGN activity with larger-scale starburst-related emissions.

Findings

All four hot DOGs detected with VLBI, confirming active nuclei.

Presence of both compact and extended radio emission components.

Evidence of AGN activity alongside starburst-related processes.

Abstract

Hot dust-obscured galaxies (hot DOGs) are a rare class of hyperluminous infrared galaxies recently identified with the Wide-field Infrared Survey Explorer (WISE) satellite. The majority of the ~1000-member all-sky population should be at high redshifts (z~2-3), at the peak of star formation in the history of the Universe. This class most likely represents a short phase during galaxy merging and evolution, a transition from starburst- to AGN-dominated phases. For the first time, we observed four hot DOGs with known mJy-level radio emission using the European VLBI Network (EVN) at 1.7 GHz, in a hope to find compact radio features characteristic to AGN activity. All four target sources are detected at ~15-30 mas angular resolution, confirming the presence of an active nucleus. The sources are spatially resolved, i.e. the flux density of the VLBI-detected components is smaller than the total flux density, suggesting that a fraction of the radio emission originates from larger-scale (partly starburst-related) activity. Here we show the preliminary results of our e-EVN observations made in 2014 February, and discuss WISE J1814+3412, an object with kpc-scale symmetric radio structure, in more detail.